Bristol weather in September

In September, Bristol sees average daytime highs of 73°F and overnight lows near 55°F, with 4.3 in of rain across 9.2 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 4th-wettest month of the year here.

Highs ease over the month, from about 77°F in the first days to 68°F by the end. The sky is clear or mostly clear about 37% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 hours at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Bristol's 2nd-clearest and 9th-windiest month. For the whole year in context, see Bristol's year-round climate.

Daytime high
73°
4th warmest
Overnight low
55°
9th coldest
Rainfall
4.3 in
9.2 wet days
Daylight
12 h 18 min
5:38 AM – 5:54 PM
Cloud cover
55%
2nd clearest
Wind
6 mph
9th windiest
Solar energy
4.19 kWh/m²
Travel score
6.9
out of 10

Bristol is city in Hartford County, Connecticut, United States.

Density
871/km²
people per km²
Founded
1785

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 77°F in the first days to 68°F by the end.

A typical September day in Bristol reaches about 73°F in the afternoon and slips back to 55°F overnight — a 18°F spread between the day's warmth and the night's chill. On most days the high lands between 64°F and 82°F. Set against its neighbours, September runs about 7°F cooler than August and about 12°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
17860
27760
37759
47759
57659
67659
77658
87658
97558
107557
117457
127457
137456
147356
157356
167355
177255
187255
197254
207154
217153
227153
237053
247052
256952
266952
276951
286851
296851
306750

How September really feels in Bristol

Once humidity and wind are folded in, September averages 0 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Bristol weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan35° / 20°3.69.56.39.30.0
Feb37° / 22°3.18.75.410.30.0
Mar45° / 29°4.311.14.511.71.1
Apr58° / 40°3.911.21.213.14.0
May68° / 49°3.811.6014.36.0
Jun77° / 59°4.511.90156.4
Jul82° / 64°4.311.2014.76.1
Aug80° / 63°4.611013.76.4
Sep73° / 55°4.39.2012.36.9
Oct61° / 44°4.49.50.210.95.2
Nov49° / 35°3.58.71.19.62.2
Dec40° / 26°4.310.24.890.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 37% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 15% of September, with mostly cloudy or overcast conditions the remaining 47%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15248
25248
35248
45149
55149
65248
75248
85347
95347
105347
115446
125446
135446
145545
155446
165446
175545
185446
195446
205347
215347
225347
235347
245248
255248
265149
275149
285149
295248
305248

Chance of precipitation in September

Any precipitation

Bristol gets around 4.3 in of rain over 9.2 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 30% and peaks near 31% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
129
229
329
429
529
629
730
830
930
1030
1130
1230
1330
1429
1529
1629
1729
1829
1929
2030
2130
2230
2330
2430
2531
2631
2731
2831
2931
3031

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the dry band about 52% of days. Sticky, muggy-or-worse air turns up on roughly 12% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1352520164
2362420154
3372320154
4382320154
5392320144
6402220144
7412220144
8422219133
9432219133
10442119133
11452118132
12472118132
13482117122
14492017122
15512017111
16522016111
17532016101
18541916101
19551915101
2056191591
2159181490
2260181480
2362171380
2463171370
2563171370
2666161260
2766161260
2868161150
2968161150
3071151040

Wind in September

Winds average 6 mph in September.

Across September, daily wind ranges from about 6 mph on the calmest days to 6 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 hours at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 84 minutes over September. Sunrise moves from 5:22 AM to 5:53 AM, and sunset from 6:21 PM to 5:29 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:226:21
212.95:236:19
312.95:246:18
412.85:256:16
512.85:266:14
612.75:276:12
712.75:286:10
812.75:296:09
912.65:306:07
1012.65:326:05
1112.55:336:03
1212.55:346:02
1312.45:356:00
1412.45:365:58
1512.35:375:56
1612.35:385:54
1712.25:395:53
1812.25:405:51
1912.15:415:49
2012.15:425:47
2112.05:435:45
2212.05:445:44
2311.95:455:42
2411.95:465:40
2511.85:475:38
2611.85:495:36
2711.75:505:35
2811.75:515:33
2911.75:525:31
3011.65:535:29

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.19 kWh/m².

For context, solar energy here swings from a low near 1.67 kWh/m² to a high of 5.96 kWh/m² in June across the year — September's 4.19 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.8Bright
24.8Bright
34.7Bright
44.7Bright
54.6Bright
64.6Bright
74.5Bright
84.5Bright
94.5Bright
104.4Bright
114.4Bright
124.3Bright
134.3Bright
144.3Bright
154.2Bright
164.2Bright
174.2Bright
184.1Bright
194.1Bright
204.0Bright
214.0Moderate
223.9Moderate
233.9Moderate
243.8Moderate
253.8Moderate
263.8Moderate
273.7Moderate
283.6Moderate
293.6Moderate
303.6Moderate
Planning a trip in September

Hazard calendar for Bristol

In seasonPeak

In September, Bristol sits inside its atlantic hurricane season. The full year is below, with each hazard's peak months called out.

Bristol sits in the Atlantic hurricane belt; the season peaks August–October.

Atlantic hurricane
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Bristol?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

6.9
Sightseeing
1st-best month of the year
5.1
Beach & pool
4th-best month of the year

September is a reasonable time to visit Bristol for sightseeing.

What to pack for Bristol in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Bristol sees daytime highs around 73°F and nights near 55°F. Worth packing: light clothes and rain gear. About 9 days see rain.

light clothesrain gear

Sea temperature near Bristol in September

The nearest coast averages about 71°F in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 38 mi away) is warmest in August at about 73°F and coldest in February near 36°F.

It's comfortable for a long swim from Jul 4 to Sep 28 — about 2.9 months when the water holds above 68°F.

30°40°50°60°70°80°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°F)Comfort
Jan39Bracing
Feb36Bracing
Mar37Bracing
Apr44Bracing
May54Bracing
Jun64Cool
Jul71Refreshing
Aug73Refreshing
Sep71Refreshing
Oct64Cool
Nov55Bracing
Dec46Bracing

UV index in Bristol in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Bristol peaks around July 11 at about 8 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 23 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJul 11UV 8Dec 23UV 1
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May7Very high
Jun7Very high
Jul8Very high
Aug5High
Sep6High
Oct3Moderate
Nov2Moderate
Dec1Low

Air quality in Bristol in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in Bristol is worst in July — around 15 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (November, 7 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1615 µg/m³Nov 197 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb11Good
Mar12Good
Apr12Good
May13Moderate
Jun14Moderate
Jul15Moderate
Aug13Moderate
Sep11Good
Oct9Good
Nov7Good
Dec8Good
Location & terrain

Where is Bristol?

Bristol sits at 41.7°N, 72.9°W, 305 ft above sea level, in United States. The nearest listed city is Plainville, 5.0 mi away.

Topography around Bristol

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Bristol.

Within 2 miles, the terrain around Bristol has significant variations in elevation — a maximum elevation change of 840 ft around an average of 545 ft above sea level; within 10 miles, significant variations in elevation — a maximum elevation change of 1,148 ft; within 50 miles, large variations in elevation — a maximum elevation change of 2,585 ft.

The land around Bristol is covered by trees (68%) within 2 miles, trees (81%) within 10 miles, and trees (77%) within 50 miles.

2 miles
840 ft
10 miles
1,148 ft
50 miles
2,585 ft
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Plainville 5.0 mi · Wolcott 5.0 mi · Southington 6.2 mi · Farmington 6.8 mi · New Britain 8.7 mi · Waterbury 9.3 mi · Avon 11 mi · Newington 12 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Bristol (41.6718°, -72.9493°, elevation 305 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).